Background and aims

Shrubs of the genus Baccharis are considered key nurse plants for the Chilean matorral, but some species have allelopathic compounds in their leaves. These compounds can leach into the soil, casting doubt on their nurse role. We assessed the nurse effect of B. paniculata, a species with allelopathic compounds in their leaves, in a central Chilean matorral site by determining the richness and cover of species growing beneath the shrub canopy and open areas, by quantifying the microclimate beneath the canopy and by experimentally assessing the microclimate versus the soil effect of this species on planted seedlings of tree dominant tree species.

Methods

Beneath shrubs and in open areas we recorded the number and cover of species as well air and soil temperature, relative humidity of the air, photosynthetic photon flux density (PPFD) and soil water content. We planted seedlings of Lithrea caustica, Quillaja saponaria, and Cryptocarya alba in both habitats using soils from open areas and from beneath Baccharis to distinguish their effects on seedling’s photochemical efficiency and survival.

Results

No woody species grew beneath B. paniculata. Air temperature was similar in both habitats, but soil temperature and PPFD were lower, and soil moisture was higher beneath shrubs. Seedling’s photochemical efficiency and survival were generally higher beneath canopies but were negatively affected by soil from beneath Baccharis shrubs.

Conclusion

Our findings question the nurse role of B. paniculata in the Chilean matorral, emphasizing the need to consider other shrub species for restoration initiatives for central Chile.

中文翻译：

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Baccharis paniculata （Asteraceae） 是智利中部 matorral 的有效护士植物吗？土壤与小气候的影响

 背景和目标

Baccharis 属的灌木被认为是智利 matoral 的关键苗生植物，但有些物种的叶子中含有化感化合物。这些化合物会渗入土壤中，使人们对它们的护士作用产生怀疑。我们通过确定生长在灌木冠层和开阔区域下的物种的丰富度和覆盖率，通过量化树冠下的小气候和实验评估小气候与土壤效应，评估了 B. paniculata（一种叶子中含有化感化合物的物种）在智利中部的护理效应树种的种植树苗。

 方法

在灌木下和开阔区域，我们记录了物种的数量和覆盖度，以及空气和土壤温度、空气的相对湿度、光合光子通量密度 （PPFD） 和土壤含水量。我们在两个栖息地种植了 Lithrea caustica、Quillaja saponaria 和 Cryptocarya alba 的幼苗，使用来自开阔区域和酒花下的土壤来区分它们对幼苗光化学效率和存活的影响。

 结果

在 B. paniculata 下没有木本物种生长。两个栖息地的气温相似，但土壤温度和 PPFD 较低，灌木下的土壤湿度较高。幼苗的光化学效率和存活率在树冠下通常较高，但受到酒花灌木下土壤的负面影响。

 结论

我们的研究结果质疑了 B. paniculata 在智利 matorral 中的护士作用，强调需要考虑其他灌木物种来恢复智利中部的恢复计划。